Having read the statement many times "Nailheads like big carburetors." Some 66 Buick motors ran Quadrajets quit successful. I have one of those Quadrajet manifolds. Will a rebuilt Quadrajet from a chevy 350 work on my 425 nailhead?
The problem with using a q-jet with the Chevrolet linkage on the nailhead manifold is that the linkage interferes with the manifold. I have a Chevrolet q-jet on my 401 and I built a spacer out of 3/4” thick aluminum stock. The nailhead really likes it.
Hi, I thought the 66 quadrajet was rated 735cfm vs the earlier Carter AFB 625cfm My 401 seemed to like the dual quad more than a Edelbrock 750 I had previously Regards,
The biggest upgrade back in the day was a 1000CFM Thermo-Quad with the 850 Thermo-Quad in 2nd. place. Which only confirms the more CFM theory. From my understanding the early Q-Jet was 750CFM & the later, I believe, '71 or '72 up was 800CFM. I haven't heard of or don't remember an 850 Q-Jet was available on ANY engine. You must remember that AFB secondary air control was weighted flaps in the rear of the carb. whereas the rear air-flap on a Q-Jet was operated by both vacuum & spring tension. They would operate more or less on air demand requirements. As an example when chassis dyno testing I noticed the rear air-flaps of the 750 Edelbrocks were not open all the way so I took 2 long screwdrivers & opened the rear flaps during WOT. The engine hesitated for a split second as if the primary accelerator pump was not working. It made NO diff. in HP or torque. Then again this was a pretty highly modified "Nail" that was capable of 7100RPM's. Even today more heavily modified it is shifted between 6200-6500RPM's. So the stock quads rated at 625CFM's each (1250CFM's total) were most likely flowing around 900-1000CFM's in stock condition, more if modified & tuned PROPERLY depending on mods to the engine. That's one of the reasons head & intake manifold porting is SO IMPORTANT. Remember, air in & air out. Tom T.
We have more some very knowledgeable Q-jet people on here, this is one; http://www.v8buick.com/index.php?members/techg8.17490/ I have used his services and am always very satisfied. He knows these cars and carbs, he is very easy to talk with and will try to steer you in the right direction. He may be able to build just what you need. You won't find a nicer guy. Website; http://www.everyday-performance.com/
